System for detecting and removing a gas bubble from a vascular infusion line

ABSTRACT

System for detecting and removing gas bubbles from a vascular infusion line, including a cassette adapted for disposition intermediate the fluid line, the cassette including a flexible tube having an inlet port for connection to a supply side of the fluid line, an outlet port configured for connection to a patient side of the fluid line, and a purge port intermediate the inlet and outlet ports, and a base unit adapted to receive the cassette and monitor fluid flow through the tube, the base unit including a sensor to detect the presence of a gas bubble in the fluid flow, a pinch valve adapted to stop the flow of fluid, and a control unit adapted to operate the base unit so that (i) fluid is permitted to flow past the pinch valve when no gas bubble is detected; and (ii) fluid flow is arrested when a gas bubble is detected.

REFERENCE TO PENDING PRIOR PATENT APPLICATIONS

This patent application claims benefit of:

(1) pending prior U.S. Provisional Patent Application Ser. No.60/573,311, filed May 21, 2004 by Ihsan A. Haddad et al. for AIRTRAP ONE(Attorney's Docket No. HAD-4 PROV); and

(2) pending prior U.S. Provisional Patent Application Ser. No.60/630,471, filed Nov. 23, 2004 by Ihsan A. Haddad et al. for ANESTHESIASAFETY PRODUCTS (Attorney's Docket No. HAD-5 PROV).

The two above-identified patent applications are hereby incorporatedherein by reference.

FIELD OF THE INVENTION

This invention relates to medical apparatus and procedures in general,and more particularly to medical apparatus and procedures forintroducing a liquid into the vascular system of a patient.

BACKGROUND OF THE INVENTION

When a patient is undergoing a medical procedure that requires theinfusion of a liquid into their circulatory system, be it venous orarterial, the introduction of a significantly-sized gas bubble (alsoknown as a “gas volume”, or a “gas bolus”, etc.) into the patient'svascular system must be avoided, since the creation of a gas embolismcan result in serious morbidity and even death.

There are two general categories of gas embolisms: venous and arterial.The primary difference between the two depends on the path by which thegas enters the vascular structure.

There are two general causes for the introduction of gas into either thearterial or venous systems:

(i) from instrumentation, such as accidental air injection throughtubing, catheters, injectors, fluid warmers, etc.; and

(ii) from physical conditions relating to the patient, such assub-atmospheric pressure in incised non-collapsed veins or veins in acoagulated operative field, etc.

Available data indicates that 2 cc's of air per kilogram of body weight,if injected into the venous system, is lethal. Smaller amounts can causevarious degrees of morbidity. To put this in perspective, the air in anempty 4 ounce cup, if injected into the veins of a 170 pound person,would typically prove lethal.

Thus, there is a need for a system for detecting and removing a gasbubble from a liquid infusion line prior to the gas bubble entering thevascular system of the patient.

SUMMARY OF THE INVENTION

The present invention provides a novel system for detecting and removinga gas bubble from a liquid infusion line before the gas bubble can enterthe vascular system of the patient. Among other things, the system isadapted to stop the flow of fluid carrying the entrapped gas bubble, andto allow for the extraction of the gas bubble prior to permitting thefluid to enter the patient's circulatory system.

In another aspect of the present invention, there is provided a novelmethod and apparatus for detecting a gas bubble in a fluid line,entrapping the gas bubble, and purging the gas bubble from the fluidline before the gas bubble can enter the patient's vascular system.

In another aspect of the present invention, there is provided a systemfor detecting and removing a gas bubble from a vascular infusion line,the system comprising:

a disposable cassette adapted for disposition intermediate the fluidline, the disposable cassette comprising:

-   -   a body; and    -   a flexible hollow tube having an inlet port being configured for        connection to the supply side of the fluid line, an outlet port        being configured for connection to the patient side of the fluid        line and a purge port located intermediate the inlet port and        the outlet port;

a base unit adapted to receive the disposable cassette and monitor fluidflow through the flexible hollow tube, wherein the base unit comprises:

-   -   a sensor adapted to detect the presence of a gas bubble in the        fluid flowing through the flexible hollow tube; and    -   a pinch valve adapted to stop the flow of fluid through the        flexible hollow tube; and

an electronic control unit adapted to operate the base unit so that (i)fluid is permitted to flow past the pinch valve when no gas bubble isdetected by the sensor; and (ii) fluid flow is arrested when a gasbubble is detected by the sensor.

In another aspect of the present invention, there is provided a systemfor detecting a gas bubble from a vascular infusion line, the systemcomprising:

a cassette adapted for disposition intermediate the fluid line, thecassette comprising:

-   -   a body; and    -   a passageway having an inlet port being configured for        connection to the supply side of the fluid line, and an outlet        port being configured for connection to the patient side of the        fluid line; and    -   a first portion of a valve for selectively arresting fluid flow        through the passageway;

a base unit adapted to receive the cassette and monitor fluid flowthrough the passageway, wherein the base unit comprises:

-   -   a sensor adapted to detect the presence of a gas bubble in the        fluid flowing through the passageway; and    -   a second portion of a valve for selectively arresting fluid flow        through the passageway; and

an electronic control unit adapted to operate the second portion of thevalve so that (i) fluid is permitted to flow past the first portion ofthe valve when no gas bubble is detected by the sensor; and (ii) fluidflow is arrested when a gas bubble is detected by the sensor.

In another aspect of the present invention, there is provided a methodfor detecting and removing a gas bubble from a vascular infusion line,the method comprising:

providing a system comprising:

a disposable cassette adapted for disposition intermediate the fluidline, the disposable cassette comprising:

-   -   a body; and    -   a flexible hollow tube having an inlet port being configured for        connection to the supply side of the fluid line, an outlet port        being configured for connection to the patient side of the fluid        line and a purge port located intermediate the inlet port and        the outlet port;

a base unit adapted to receive the disposable cassette and monitor fluidflow through the flexible hollow tube, wherein the base unit comprises:

-   -   a sensor adapted to detect the presence of a gas bubble in the        fluid flowing through the flexible hollow tube; and    -   a pinch valve adapted to stop the flow of fluid through the        flexible hollow tube; and

an electronic control unit adapted to operate the base unit so that (i)fluid is permitted to flow past the pinch valve when no gas bubble isdetected by the sensor; and (ii) fluid flow is arrested when a gasbubble is detected by the sensor;

initiating fluid flow through the disposable cassette; and

monitoring the fluid flowing through the disposable cassette for theoccurrence of a gas bubble and, if a gas bubble is detected, arrestingthe flow of fluid through the fluid line.

In another aspect of the present invention, there is provided a methodfor detecting a gas bubble from a vascular infusion line, the methodcomprising:

providing a system comprising:

a cassette adapted for disposition intermediate the fluid line, thecassette comprising:

-   -   a body; and    -   a passageway having an inlet port being configured for        connection to the supply side of the fluid line, and an outlet        port being configured for connection to the patient side of the        fluid line; and    -   a first portion of a valve for selectively arresting fluid flow        through the passageway;

a base unit adapted to receive the cassette and monitor fluid flowthrough the passageway, wherein the base unit comprises:

-   -   a sensor adapted to detect the presence of a gas bubble in the        fluid flowing through the passageway; and    -   a second portion of a valve for selectively arresting fluid flow        through the passageway;

an electronic control unit adapted to operate the second portion of thevalve so that (i) fluid is permitted to flow past the first portion ofthe valve when no gas bubble is detected by the sensor; and (ii) fluidflow is arrested when a gas bubble is detected by the sensor;

initiating fluid flow through the cassette; and

monitoring the fluid flowing through the cassette for the occurrence ofa gas bubble and, if a gas bubble is detected, arresting the flow offluid through the fluid line.

In another aspect of the present invention, there is provided a systemfor detecting and removing a gas bubble from a flexible vascularinfusion line, the system comprising:

a cassette adapted for disposition intermediate the fluid line, thecassette comprising:

-   -   a body; and    -   a passageway having an inlet port being configured for        connection to the supply side of the fluid line and an outlet        port configured for connection to the patient side of the fluid        line;

a base unit adapted to receive the cassette and monitor fluid flowthrough the passageway, wherein the base unit comprises:

-   -   a sensor adapted to detect the presence of a gas bubble in the        fluid flowing through the passageway;

an electronic control unit disposed adjacent to the flexible fluid line,upstream of the cassette, wherein the electronic control unit comprisesa valve for selectively arresting fluid flow through the flexible fluidline and circuitry for communicating with the sensor and operating thevalve so that (i) fluid is permitted to flow through the flexible fluidline when no gas bubble is detected by the sensor; and (ii) fluid flowthrough the flexible fluid line is arrested when a gas bubble isdetected by the sensor; and

a purge port located upstream of the patient and downstream of theelectronic control unit.

In another aspect of the present invention, there is provided a methodfor detecting and removing a gas bubble from a flexible vascularinfusion line, the method comprising:

providing a system comprising:

a cassette adapted for disposition intermediate the fluid line, thecassette comprising:

-   -   a body; and    -   a passageway having an inlet port being configured for        connection to the supply side of the fluid line and an outlet        port configured for connection to the patient side of the fluid        line;

a base unit adapted to receive the cassette and monitor fluid flowthrough the passageway, wherein the base unit comprises:

-   -   a sensor adapted to detect the presence of a gas bubble in the        fluid flowing through the passageway;

an electronic control unit disposed adjacent to the flexible fluid line,upstream of the cassette, wherein the electronic control unit comprisesa valve for selectively arresting fluid flow through the flexible fluidline and circuitry for communicating with the sensor and operating thevalve so that (i) fluid is permitted to flow through the flexible fluidline when no gas bubble is detected by the sensor; and (ii) fluid flowthrough the flexible fluid line is arrested when a gas bubble isdetected by the sensor; and

a purge port located upstream of the patient and downstream of theelectronic control unit;

initiating fluid flow through the flexible fluid line and through thecassette; and

monitoring the fluid flowing through the cassette for the occurrence ofa gas bubble and, if a gas bubble is detected, arresting the flow offluid through the flexible fluid line.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of the present invention will bemore fully disclosed or rendered obvious by the following detaileddescription of the preferred embodiments of the invention, which are tobe considered together with the accompanying drawings wherein likenumbers refer to like parts, and further wherein:

FIG. 1 is a schematic view showing a disposable cassette formed inaccordance with the present invention;

FIGS. 2-4 are schematic views showing components of the disposablecassette shown in FIG. 1;

FIG. 5 is a schematic view showing a base unit formed in accordance withthe present invention;

FIG. 6 is a schematic view showing a component of the base unit shown inFIG. 5;

FIGS. 7 and 8 are schematic views showing the disposable cassette ofFIG. 1 mounted on the base unit of FIG. 5;

FIG. 9 is a schematic view showing the disposable cassette's sensor loopand delay loop;

FIG. 10 is a schematic view showing an electronic control unit formed inaccordance with the present invention;

FIG. 11 is a schematic view showing an alternative form of thedisposable cassette;

FIG. 12 is a schematic view showing the tubing component of thedisposable cassette shown in FIG. 11;

FIG. 13 is another schematic view of the disposable cassette shown inFIG. 11;

FIG. 14 is a schematic view showing an alternative form of base unit;

FIGS. 15 and 16 are schematic views showing the disposable cassette ofFIGS. 11 and 13 in conjunction with the base unit of FIG. 14;

FIGS. 17 and 18 are schematic views showing an alternative form of thedisposable cassette;

FIGS. 19 and 20 are schematic views showing an alternative form of thebase unit;

FIG. 21 is a schematic view showing the disposable cassette of FIGS. 17and 18 in conjunction with the base unit of FIGS. 19 and 20;

FIG. 22 is a schematic view showing an alternative form of thedisposable cassette;

FIGS. 23 and 24 are schematic views showing the disposable cassette ofFIG. 22 in conjunction with an alternative base unit;

FIG. 25 is a schematic view showing another alternative form of thedisposable cassette;

FIGS. 26-34 are various schematic views showing another preferredembodiment of the new system for detecting a gas bubble in a fluid line,entrapping the gas bubble, and purging the gas bubble before the gasbubble can enter the patient's vascular system;

FIG. 35 is a schematic view showing an alternative disposable cassettein conjunction with an alternative base incorporating the sensing unitfor remote mounting;

FIG. 36 is a schematic view of an alternative electrical control unitincorporating a pinch valve; and

FIG. 37 is a schematic view showing a system configuration where thealternative disposable cassette of FIG. 35, the alternative base unit ofFIG. 35, and the alternative electrical control unit of FIG. 36 are allmounted on an IV pole.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention provides a novel system for detecting a gas bubblein a fluid line, entrapping the gas bubble, and purging the gas bubblebefore the gas bubble can enter the patient's vascular system.

In one preferred form of the invention, the novel system comprises threecomponents: (i) a disposable cassette for disposition intermediate thefluid line, wherein fluid flowing through the disposable cassette may bemonitored and, if a gas bubble is detected within the fluid flow, thefluid flow may be stopped and the gas bubble removed before continuingthe fluid flow; (ii) a base unit providing apparatus for monitoring thefluid flow through the disposable cassette and, if a gas bubble isdetected, selectively stopping the fluid flow through the disposablecassette while the gas bubble is removed; and (iii) an electroniccontrol unit for operating the base unit.

More particularly, and looking now at FIGS. 1-4, there is shown adisposable cassette 5 which comprises one preferred form of theinvention. Disposable cassette 5 is adapted for disposition intermediatethe fluid line (e.g., an IV line), wherein fluid flowing through thedisposable cassette may be monitored and, if a gas bubble (e.g., an airbubble) is detected within the fluid flow, the fluid flow may be stoppedand the gas bubble removed before continuing the fluid flow. Disposablecassette 5 comprises a body 10 including tubing 15 (FIG. 1). Tubing 15has an inlet port 20, and outlet port 25, and a purge port 30. Body 10and tubing 15 are arranged so that tubing 15 is exposed at a sensorstation 35 and at a pinch location 40 (e.g., with openings). Inlet port20 and outlet port 25 are configured with an appropriate fitting (i.e.,Luer, male, female, locking “T”, stopcock, etc.) so that the tubing 15of the disposable cassette 5 can be connected intermediate a fluid lineentering the patient. Purge port 30 provides selective access (e.g., viaa removable cap) to the interior of tubing 15, whereby to permit removalof a gas bubble in the fluid line, as will hereinafter be discussed. Inone preferred form of the invention, disposable cassette 5 can be formedby providing a groove 45 in body 10 (FIG. 2), wherein groove 45 isconfigured to receive tubing 15 (FIG. 3), with a cover 50 (FIG. 4)securing the tubing 15 within groove 45.

Body 10 and cover 50 are preferably formed out of medical grade, soft orsemi-soft, sterilizable, clear or transparent or semi-transparent,plastic such as PVC, a urethane, etc.

Tubing 15 is preferably a clear plastic FDA Class 6 tubing with adurometer consistent with the “pinch” requirements of the base unit'spinch valve, as will hereinafter be discussed. Tubing 15 is sized so asto be consistent with the flow requirements of the IV fluid line. By wayof example but not limitation, for adults and high flow IV requirements,a tube 15 having a ⅛ inch inside diameter, and a 3/16 inch outsidediameter, may be used.

Preferably the disposable cassette 5 is provided to the user in apre-assembled form (i.e., with tubing 15 loaded into groove 45 andsealed in place with cover 50), with the disposable cassette beingsealed in a sterilized package which is opened at the time of use.

Looking next at FIGS. 5-9, there is shown a base unit 100 whichcomprises one preferred form of the invention. Base unit 100 is adaptedto receive disposable cassette 5 and monitor the fluid flow through thedisposable cassette and, if a gas bubble is detected, selectively stopthe fluid flow through the disposable cassette while the gas bubble isremoved. Base unit 100 generally comprises a seat 105 (FIG. 5) forseating the disposable cassette 5. Base unit 100 also comprises a sensor110 for detecting the presence of a gas bubble in the fluid flowingthrough tubing 15 of the disposable cassette. In one form of theinvention, sensor 110 comprises an ultrasound sensor (FIG. 6) and, inone particularly preferred form of the invention, sensor 110 comprisesan ultrasound sensor having two halves 110A, 110B hinged together at110C. Each half 110A, 110B comprises an appropriate rectangularultrasound crystal C running the length of the face. Base unit 100 alsocomprises a pinch valve 115 (FIG. 5) for selectively pinching off thetubing 15 of disposable cassette 5, whereby to selectively stop fluidflow through the tubing. By way of example but not limitation, pinchvalve 115 may comprise a solenoid having a movable member for (i)engaging the tubing 15 when the movable member is placed into itsextended position, whereby to pinch the tubing 15 closed, and (ii)disengaging the tubing 15 when the movable member is placed into itsretracted position, whereby to allow the tubing to expand to its fulldiameter. As seen in FIGS. 7 and 8, disposable cassette 5 and base unit100 are constructed so that when disposable cassette 5 is received onseat 105, sensor station 35 of disposable cassette 5 is positionedadjacent to sensor 110 of base unit 100, and pinch location 40 ofdisposable cassette 5 is disposed adjacent to pinch valve 115 of baseunit 100.

Significantly, and as will hereinafter be discussed in further detail,due to the switchback configuration of the tubing 15 of disposablecassette 5, two legs of tubing 15 will pass by sensor 110 at sensorstation 35 (FIGS. 7 and 9). Thus, tubing 15 will be monitored by sensor110 at two locations, L1 and L2. The length of tubing 15 extendingbetween the two locations L1 and L2 may be referred to as the “sensorloop” SL.

Furthermore, it will be appreciated that a length of tubing extendsbetween sensor location L2 and purge port 30. This length of tubingprovides a “delay loop” DL which will hereinafter be discussed.

Looking next at FIG. 10, there is shown an electronic control unit 200which comprises one preferred form of the invention. Electronic controlunit 200 is adapted to operate base unit 100 as will hereinafter bediscussed. Electronic control unit 200 generally comprises a housing203, an on/off switch 205, a sound off switch 210, a system reset switch215, a green light 220, a system red light 225, a sound red light 230,an umbilical cord 235 for connecting electronic control unit 200 to baseunit 100, and various conventional electronic components (not shown)housed by housing 203 and adapted to operate as will hereinafter bediscussed.

Among other things, umbilical cord 235 connects electronic control unit200 to the base unit's sensor 110 whereby to operate (i.e., power andread) the same, and umbilical cord 235 connects electronic control unit200 to the base unit's pinch valve 115, whereby to operate (i.e., powerand control) the same.

Electronic control unit 200 is preferably internally powered by a 12volt rechargeable battery pack, although it may also be powered by anexternal power source, e.g., by connection to a wall plug.

In operation, a disposable cassette 5 is withdrawn from its sterilizedpackage and loaded into base unit 100. This is done by opening sensor110, seating disposable cassette 5 on the base unit's seat 105 so thatthe cassette's sensor station 35 is located adjacent to the base unit'ssensor 110 and so that the disposable cassette's pinch location 40 islocated adjacent to the base unit's pinch valve 115, and then closingsensor 110.

Next, the “source side” of a fluid line (e.g., an IV line) is connectedto the cassette's inlet port 20, and the cassette's output port 25 isconnected to the “patient side” of the IV line.

The IV line is then primed, air removed, etc. so that the fluid line isready to infuse the patient.

Then the system is turned on by pushing on/off switch 205.

Next, fluid is allowed to flow from the fluid source into tubing 15 ofdisposable cassette 5. As the fluid flows through the tubing, sensor 110monitors the fluid flow, sensing for the presence of a gas bubble. Solong as no gas bubble is detected, the fluid is allowed to flowuninterrupted, thereby infusing the patient with the desired fluid.Green light 220 is lit when the system is on and no gas bubble isdetected by sensor 110.

In the event that sensor 110 detects the presence of a gas bubble (e.g.,an air bubble) in the fluid, electronic control unit 200 turns on redlight 225, sounds an audible alarm in electronic control unit 200, andactivates pinch valve 115, thereby arresting the fluid flow.

The operator can now activate the sound off switch 210, temporarilyturning the alarm sound off, and then use purge port 30 to bleed the gasbubble from the system. As soon as the sensor no longer detects a gasbubble at sensor station 35, indicating that the gas bubble has beenpurged from the line, green light 220 comes back on, signifying that thesystem may now be reset. The operator then actuates system reset switch215, thereby resetting the system. Upon system reset, pinch valve 115 isre-opened, thereby permitting the fluid flow to resume.

In the event that the sound off switch 210 is pushed, but the systemfault is not corrected within some specified time period (e.g., oneminute), the electronic control unit 200 then turns the sound alarm backon.

In the event that the reset switch 215 is activated, but the faultcondition is not corrected, the system will not reset.

It should be appreciated that, as noted above, the disposable cassette'stubing 15 passes by sensor 110 at two locations, i.e., L1 and L2.

If desired, the system can be configured such that sensor 110 andelectronic control unit 200 trigger a fault condition when a gas bubbleis detected at either location L1 or L2.

More preferably, however, the system is configured such that sensor 110and electronic control unit 200 trigger a fault condition only when agas volume is simultaneously detected at both locations L1 and L2. Thisconfiguration can be advantageous, inasmuch as simultaneously detectinga gas bubble at both locations L1 and L2 can be indicative of thepresence of a large gas bubble in the fluid line, i.e., one completelyfilling the sensor loop SL. As a result, by configuring the disposablecassette 5 so that its sensor loop SL is of a pre-determined size, thesystem can discriminate between gas bubbles of different sizes,activating the fault condition only when the gas bubble exceeds acertain size. In other words, in this form of the invention, the lengthof the sensor loop SL, and its internal volume, determines the amount ofgas that can be present in the circuit before the fault condition istriggered. This feature can be advantageous, inasmuch as adults may becapable of safely tolerating a larger gas bubble than an infant, etc.Furthermore, gas bubbles commonly exist in most IV circuits; tiny gasbubbles are generally deemed harmless, and it is only the larger gasbubbles which are considered to pose a threat to the patient. By makingthe system capable of discriminating between different bubble sizes whendetermining a fault condition, false positives can be minimized withoutsacrificing system usefulness.

In one preferred form of the invention, sensor loop SL is configured tohave a volume of 1 cc.

It should also be appreciated that various system components typicallyhave response time delays associated with them. Thus, for example, thereis typically a delay between when a fault condition occurs at locationsL1 and/or L2, and when the fault condition is detected by sensor 110,and when the pinch valve 115 can be closed. To this end, it isadvantageous to provide a delay loop DL between sensor station 35 andpurge port 30. By properly setting the length of delay loop DL relativeto the aggregated response delay times of the system components, thesystem can be provided with the capacity to timely stop the fluid flowand reliably trap the undesirable gas volume in the delay loop for saferemoval of the same.

In one preferred form of the invention, delay loop DL is configured tohave a length of 10 cm.

Disposable cassette 5 is preferably discarded after use.

Looking next at FIGS. 11-16, there are shown alternative constructionsfor disposable cassette 5 and base unit 100. Among other things, thisform of the invention utilizes (i) a different and more compact geometrythan that shown in FIGS. 1-10; (ii) a one-piece sensor 110; and (iii) avacuum-formed cassette body 10 which encompasses portions of tubing 15,whereby to eliminate the use of body grooves 45 and cover 50.

Looking next at FIGS. 17-21, there are shown other alternativeconstructions for disposable cassette 5 and base unit 100. Among otherthings, this form of the invention utilizes (i) a different and morecompact geometry than that shown in FIGS. 1-16; (ii) a disposablecassette 5 omitting the large planar body 10 and cover 50, with tubing15 in the form of an inline stacked configuration and secured together(e.g., with glue, molding techniques, etc.) so as to form the structureof disposable cassette 5 (here, the securing structure can be thought ofas constituting the body 10); and (iii) a base unit 100 modified toreceive the modified disposable cassette 5.

Looking next at FIGS. 22-24, there are shown further alternativeconstructions for disposable cassette 5 and base unit 100. Among otherthings, this form of the invention utilizes (i) a different and morecompact geometry than that shown in FIGS. 1-21; (ii) a disposablecassette 5 having an L-shaped body 10, with tubing 15 in the form of aninline stacked coil configuration and secured together (e.g., with glue,molding techniques, etc.); and (iii) a base unit 100 utilizing amanually cocked pinch valve 15. This manual pinch valve construction canbe advantageous in further reducing the size of the pinch valve andhence reducing the size of the base unit 100. In this embodiment of theinvention, after fault detection and correction, the system has to bereset manually by compressing the valve's spring-loaded pinch bar untilit is cocked in place. Upon the detection of a gas bubble in the sensorloop, the locking mechanism is electronically released.

Looking next at FIG. 25, it will be seen that the geometry of thedisposable cassette's tubing 15 can be arranged as desired so as toprovide the desired sensor loop SL and delay loop DL.

Looking next at FIGS. 26-34, there is shown still another novel systemfor detecting and removing a gas bubble from a liquid infusion line. Inthis form of the invention, the base unit 100 and the electronic controlunit 200 are contained in the same housing. Also shown is a detachablebattery pack 300 for powering the system.

System with Automatic Fluid Diversion

The system described above is adapted to stop fluid flow to the patientupon the detection of a gas bubble, and then requires the operator tointervene by manually bleeding the gas bubble out of the line and thenresetting the system.

In an alternative construction, this intervention is automated in thesense that, upon detection of a gas bubble, the flow of liquid (e.g. IVliquid) is diverted to a collection bag until the sensor 110 once againdetects liquid in the IV line. When sensor 110 again detects liquid inthe IV line, the gas bubble between sensor 110 and the flow divertingmechanism is flushed out of the system before flow is diverted back tothe patient. This can be accomplished in various ways. By way of examplebut not limitation:

(i) at the onset of a procedure, the operator can set a control on theelectronic control unit 200 to reflect the estimated IV flow rate—thisflow rate sets a time delay for the diverting mechanism, whereby todelay the diversion of the flow back to the patient after sensor 110once again detects liquid; or

(ii) a second gas bubble sensor (not shown) can be positioned in thesystem, at the diverting mechanism, to control switching the fluid flowback to the patient after sensor 110 and the second gas bubble sensorboth detect liquid in the line.

The diverting mechanism can take many different forms. For example, thediverting mechanism can be a disposable Y connector molded into thedisposable cartridge 5 and an integral part of the disposable cartridge,with the bottom part of the Y connected to sensor 110, downstream fromthe liquid delay loop DL of the disposable cartridge 5. The second gasbubble sensor is positioned to detect a gas bubble in the central partof the Y. A two-sided pinch valve 115 is attached to the two top partsof the Y; this pinch valve has two pinching stations, and is arranged sothat when one station is open, the other station is closed. A normallyopen side of pinch valve 115 is positioned at one of the top forks ofthe Y and the normally closed part of the pinch valve 115 is positionedon the other side of the fork in the top part of the Y. Simpleactivation of the pinch valve 115 now will allow the flow to be divertedfrom one side of the disposable cartridge Y to the other. Theappropriate side will be connected to the patient; the other side isconnected to the collection bag.

A further device configuration would allow for yet a third gas bubblesensor (not shown) to be incorporated in the device. The third gasbubble sensor can be a clamp-on sensor to be positioned on the tubingslightly downstream from the IV bag or other fluid source, to detectwhen the IV bag is empty, to halt the flow or divert it from the patientand then sound an alarm, signaling an empty IV bag.

In the preceding disclosure, means were disclosed for selectivelydiverting the flow of fluid away from the patient (when the fluid flowcontains a gas bubble) and then an automatic resumption of fluid flow tothe patient (when the gas bubble has been purged from the line).

In another form of the invention, the fluid flow, upon detection of agas bubble, is automatically diverted away from the patient using any ofseveral methods disclosed above or any other suitable means fordiverting the gas embolus and maintaining the safety of the patient; butthen the fluid flow is not automatically diverted back to the patientbut, rather, continues to be directed away from the patient until theattendant resets the device. This will allow the attendant to assess thesituation and reset the system when appropriate.

The above embodiments can be incorporated singly or in combination withany of the other system iterations.

An alternate electronic method to trigger the pinch valve 115, or toreroute the fluid flow to a collection bag or back to the patient,entails the electronic calculation of the time the sensor 110 senses agas bubble in the tubing. By way of example, if a quantity of gas ispassing through the sensor 110, an electronic signal signifying “gas” istriggered at the onset of the gas bolus, and the electronic control unit200 senses the time that the “gas signal” came on. The internalcross-sectional area of the tubing 15 is known. An automatic calculationis performed as to the gas volume passing through the line. If onesensor is used, the gas volume passing through is calculated using anassumed flow rate. This also allows for the calculation of the velocityof the fluid. In turn, this allows for the calculation of the pressuredrop in the tubing, allowing for a volume adjustment of the gas flowingthrough. This calculation is done in real-time and continuously updatesits information and, when a predetermined gas volume is sensed, thesystem triggers its mode of action (e.g., shuts off, alarms, diverts theflow, etc.).

For more precise performance, the use of two sensors in series,positioned a known distance apart, may be utilized. The sensorconfiguration and positioning should follow the basic parameters of thesystem, allowing sufficient time for action before releasing the fluidto the patient.

Modifications

Various modifications can be made to the embodiments disclosed above. Byway of example but not limitation:

(1) the sensor 110 can use IR (infra red) to detect the presence of agas bubble;

(2) the sensor 110 can use electrical resistance to detect the presenceof a gas bubble;

(3) the sensor 110 can use sound-based technologies (e.g., Dopplertechnology) to detect the presence of a gas bubble;

(4) the sensor 110 can comprise a float in the liquid circuit to gatefluid flow: with this arrangement, the float rises in the presence ofliquid, opening an outlet port, but the float sinks in the presence of agas bubble, closing an outlet port—a resistance or a magnetic detectorthen senses the float position and signals a system fault;

(5) safety devices can be incorporated to automatically indicate correct(or incorrect) engagement of the disposable cassette 5 on base unit 100;

(6) an indicator may be provided to show delivery of an adequatetube-pinching force;

(7) a wireless connection may be provided between base unit 100 andelectronic control unit 200—thus, for example, and looking now at FIG.35, a disposable cassette 5 and base unit 100 may be separated fromelectronic control unit 200, with the units communicating through awireless connection; or, if desired, the pinch valve 115 may be locatedwith the electronic control unit 200 (FIG. 36) and/or, if desired,disposable cassette 5, base unit 100 and electronic control unit 200 mayall be mounted from an IV pole (FIG. 37);

(8) the sensor station 35 of the disposable cassette 5 (which ispositioned adjacent to sensor 110) may be treated with an ultrasoundcoupling medium such as Vaseline, or a water jell, or whatever isappropriate, so as to ensure a satisfactory coupling to the ultrasoundsensor 110—the coating may also contain a solvent and/or an abrasive toclean the sensor 110 and sensor station 35;

(9) as an alternative or in combination with the foregoing, means couldbe provided to clean the sensor 110 as the disposable cassette 5 ismounted adjacent to the sensor 110—by way of example, this could beaccomplished by a mechanical shield covering the disposable tubing 15which, when removed, will clean the sensor cavity;

(10) cassette 5 need not be disposable—it could be reusable if desired;

(11) cassette 5 could be formed with a passageway, wherein only portionsof the passageway comprise flexible tubing—the remainder of thepassageway could be formed as a flow path through body 10, or as rigidtubing, etc.;

(12) the construction can be something other than flexible tubing and apinch valve to selectively close off fluid flow—by way of example butnot limitation, cassette 5 could include a traditional flow valve, andbase unit 100 could include a mechanism (e.g., a solenoid) for openingthat flow control valve; and

(13) if desired, the purge port can be omitted.

Further Modifications

It will be appreciated that still further embodiments of the presentinvention will be apparent to those skilled in the art in view of thepresent disclosure. It is to be understood that the present invention isby no means limited to the particular constructions herein disclosedand/or shown in the drawings, but also comprises any modifications orequivalents within the scope of the invention.

1. A system for detecting and removing a gas bubble from a vascularinfusion line, the system comprising: a disposable cassette adapted fordisposition intermediate the fluid line, the disposable cassettecomprising: a body; and a flexible hollow tube having an inlet portbeing configured for connection to the supply side of the fluid line, anoutlet port being configured for connection to the patient side of thefluid line and a purge port located intermediate the inlet port and theoutlet port; a base unit adapted to receive the disposable cassette andmonitor fluid flow through the flexible hollow tube, wherein the baseunit comprises: a sensor adapted to detect the presence of a gas bubblein the fluid flowing through the flexible hollow tube; and a pinch valveadapted to stop the flow of fluid through the flexible hollow tube; andan electronic control unit adapted to operate the base unit so that (i)fluid is permitted to flow past the pinch valve when no gas bubble isdetected by the sensor; and (ii) fluid flow is arrested when a gasbubble is detected by the sensor.
 2. A system according to claim 1wherein the body of the disposable cassette comprises a grooveconfigured to receive the flexible hollow tube.
 3. A system according toclaim 2 wherein the disposable cassette additionally comprises a coverfor securing the flexible hollow tube within the groove.
 4. A systemaccording to claim 1 wherein the body of the disposable cassetteencompasses at least a portion of the flexible hollow tube.
 5. A systemaccording to claim 1 wherein the disposable cassette comprises aflexible hollow tube arranged in an inline configuration, and furtherwherein the body comprises the structure for stabilizing the flexiblehollow tube in this configuration.
 6. A system according to claim 5wherein the flexible hollow tube is arranged in a stacked inlineconfiguration.
 7. A system according to claim 5 wherein the flexiblehollow tube is arranged in a planar inline configuration.
 8. A systemaccording to claim 1 wherein the body has an L-shaped configuration. 9.A system according to claim 1 wherein the flexible hollow tubing isarranged in a switchback configuration so as to create a sensor loop.10. A system according to claim 9 wherein the sensor loop is sized so asto have a volume of approximately 1 cc.
 11. A system according to claim1 wherein, when the disposable cassette is mounted to the base unit, theportion of the flexible hollow tube located adjacent the sensor isdisplaced from the purge port so as to create a delay loop.
 12. A systemaccording to claim 11 wherein the delay loop is configured to have alength of approximately 10 cm.
 13. A system according to claim 1 whereinthe body of the disposable cassette comprises an opening to facilitatepositioning of the flexible hollow tube adjacent to the sensor.
 14. Asystem according to claim 1 wherein the body of the disposable cassettecomprises an opening to facilitate positioning of the flexible hollowtube adjacent to the pinch valve.
 15. A system according to claim 1wherein the sensor comprises an ultrasound sensor.
 16. A systemaccording to claim 1 wherein the sensor comprises two halves hingedtogether.
 17. A system according to claim 1 wherein the sensor is aninfra red sensor.
 18. A system according to claim 1 wherein the sensorutilizes electrical resistance to detect the presence of a gas bubble.19. A system according to claim 1 wherein the sensor utilizes Dopplertechnology to detect the presence of a gas bubble.
 20. A systemaccording to claim 1 wherein the sensor comprises (i) a floatable devicedisposed in the fluid which rises in the presence of liquid and sinks inthe presence of a gas bubble; and (ii) apparatus for detecting theposition of the floatable device.
 21. A system according to claim 1wherein the sensor is adapted to simultaneously detect the presence of agas bubble in the fluid flowing through at least two portions of theflexible hollow tube.
 22. A system according to claim 21 wherein theflexible hollow tube is configured so that the two portions are adjacentto one another.
 23. A system according to claim 1 wherein the pinchvalve is manually cocked.
 24. A system according to claim 1 wherein thepinch valve comprises a solenoid.
 25. A system according to claim 1wherein the pinch valve is configured so as to selectively collapse thewall of the flexible hollow tube whereby the arrest the flow of fluid.26. A system according to claim 1 wherein the electronic control unit ishard-wired to the base unit.
 27. A system according to claim 1 whereinthe electronic control unit is in wireless communication with the baseunit.
 28. A system according to claim 1 wherein the electronic controlunit internally powered by a rechargeable power supply.
 29. A systemaccording to claim 1 wherein the electronic control unit internallypowered by an external power source.
 30. A system for detecting a gasbubble from a vascular infusion line, the system comprising: a cassetteadapted for disposition intermediate the fluid line, the cassettecomprising: a body; and a passageway having an inlet port beingconfigured for connection to the supply side of the fluid line, and anoutlet port being configured for connection to the patient side of thefluid line; and a first portion of a valve for selectively arrestingfluid flow through the passageway; a base unit adapted to receive thecassette and monitor fluid flow through the passageway, wherein the baseunit comprises: a sensor adapted to detect the presence of a gas bubblein the fluid flowing through the passageway; and a second portion of avalve for selectively arresting fluid flow through the passageway; andan electronic control unit adapted to operate the second portion of thevalve so that (i) fluid is permitted to flow past the first portion ofthe valve when no gas bubble is detected by the sensor; and (ii) fluidflow is arrested when a gas bubble is detected by the sensor.
 31. Asystem according to claim 30 wherein the first portion of the valve isformed by providing the passageway with a flexible wall capable of beingdeformed so as to close off the passageway to fluid flow.
 32. A systemaccording to claim 31 wherein the second portion of the valve comprisesan actuator for deforming the flexible wall of the passageway.
 33. Asystem according to claim 30 wherein the first portion of the valvecomprises a valve housing, a valve seat and a valve member for selectiveengagement with the seat, and wherein the second portion of the valvecomprises an actuator for moving the valve member.
 34. A method fordetecting and removing a gas bubble from a vascular infusion line, themethod comprising: providing a system comprising: a disposable cassetteadapted for disposition intermediate the fluid line, the disposablecassette comprising: a body; and a flexible hollow tube having an inletport being configured for connection to the supply side of the fluidline, an outlet port being configured for connection to the patient sideof the fluid line and a purge port located intermediate the inlet portand the outlet port; a base unit adapted to receive the disposablecassette and monitor fluid flow through the flexible hollow tube,wherein the base unit comprises: a sensor adapted to detect the presenceof a gas bubble in the fluid flowing through the flexible hollow tube;and a pinch valve adapted to stop the flow of fluid through the flexiblehollow tube; and an electronic control unit adapted to operate the baseunit so that (i) fluid is permitted to flow past the pinch valve when nogas bubble is detected by the sensor; and (ii) fluid flow is arrestedwhen a gas bubble is detected by the sensor; initiating fluid flowthrough the disposable cassette; and monitoring the fluid flowingthrough the disposable cassette for the occurrence of a gas bubble and,if a gas bubble is detected, arresting the flow of fluid through thefluid line.
 35. A method according to claim 34 including the furtherstep of removing a detected gas bubble through the purge port.
 36. Amethod for detecting a gas bubble from a vascular infusion line, themethod comprising: providing a system comprising: a cassette adapted fordisposition intermediate the fluid line, the cassette comprising: abody; and a passageway having an inlet port being configured forconnection to the supply side of the fluid line, and an outlet portbeing configured for connection to the patient side of the fluid line;and a first portion of a valve for selectively arresting fluid flowthrough the passageway; a base unit adapted to receive the cassette andmonitor fluid flow through the passageway, wherein the base unitcomprises: a sensor adapted to detect the presence of a gas bubble inthe fluid flowing through the passageway; and a second portion of avalve for selectively arresting fluid flow through the passageway; anelectronic control unit adapted to operate the second portion of thevalve so that (i) fluid is permitted to flow past the first portion ofthe valve when no gas bubble is detected by the sensor; and (ii) fluidflow is arrested when a gas bubble is detected by the sensor; initiatingfluid flow through the cassette; and monitoring the fluid flowingthrough the cassette for the occurrence of a gas bubble and, if a gasbubble is detected, arresting the flow of fluid through the fluid line.37. A method according to claim 36 including the further step ofremoving a detected gas bubble through the purge port.
 38. A system fordetecting and removing a gas bubble from a flexible vascular infusionline, the system comprising: a cassette adapted for dispositionintermediate the fluid line, the cassette comprising: a body; and apassageway having an inlet port being configured for connection to thesupply side of the fluid line and an outlet port configured forconnection to the patient side of the fluid line; a base unit adapted toreceive the cassette and monitor fluid flow through the passageway,wherein the base unit comprises: a sensor adapted to detect the presenceof a gas bubble in the fluid flowing through the passageway; anelectronic control unit disposed adjacent to the flexible fluid line,upstream of the cassette, wherein the electronic control unit comprisesa valve for selectively arresting fluid flow through the flexible fluidline and circuitry for communicating with the sensor and operating thevalve so that (i) fluid is permitted to flow through the flexible fluidline when no gas bubble is detected by the sensor; and (ii) fluid flowthrough the flexible fluid line is arrested when a gas bubble isdetected by the sensor; and a purge port located upstream of the patientand downstream of the electronic control unit.
 39. A method fordetecting and removing a gas bubble from a flexible vascular infusionline, the method comprising: providing a system comprising: a cassetteadapted for disposition intermediate the fluid line, the cassettecomprising: a body; and a passageway having an inlet port beingconfigured for connection to the supply side of the fluid line and anoutlet port configured for connection to the patient side of the fluidline; a base unit adapted to receive the cassette and monitor fluid flowthrough the passageway, wherein the base unit comprises: a sensoradapted to detect the presence of a gas bubble in the fluid flowingthrough the passageway; an electronic control unit disposed adjacent tothe flexible fluid line, upstream of the cassette, wherein theelectronic control unit comprises a valve for selectively arrestingfluid flow through the flexible fluid line and circuitry forcommunicating with the sensor and operating the valve so that (i) fluidis permitted to flow through the flexible fluid line when no gas bubbleis detected by the sensor; and (ii) fluid flow through the flexiblefluid line is arrested when a gas bubble is detected by the sensor; anda purge port located upstream of the patient and downstream of theelectronic control unit; initiating fluid flow through the flexiblefluid line and through the cassette; and monitoring the fluid flowingthrough the cassette for the occurrence of a gas bubble and, if a gasbubble is detected, arresting the flow of fluid through the flexiblefluid line.